The background description provided herein is for the purpose of generally presenting the context of the present invention. The subject matter discussed in the background of the invention section should not be assumed to be prior art merely as a result of its mention in the background of the invention section. Similarly, a problem mentioned in the background of the invention section or associated with the subject matter of the background of the invention section should not be assumed to have been previously recognized in the prior art. The subject matter in the background of the invention section merely represents different approaches, which in and of themselves may also be inventions. Work of the presently named inventors, to the extent it is described in the background of the invention section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.
Nanocarbon materials have widespread applications, especially in the field of electrochemical energy storages, catalyst preparations, transparent conductive films, conductive materials, reinforced materials, adsorption and desorption materials, and so on. Among them, sp2 hybridization based nanocarbon materials have excellent mechanical flexibility and conductivity. For example, the sp2 hybridization based carbon atoms can form two-dimensional (2-D) graphene, which has a large specific surface area, as well as excellent conductive and mechanical properties. The 2-D graphene crimps together, thereby forming carbon nanotubes with 1-D tubular structure. These carbon nanotubes have high length-to-diameter ratio and excellent conductivity and mechanical strength. Meanwhile, the sp2 hybridization based carbon atoms can also form 0-D graphene ball (C60), which has peculiar electronic effects. Clearly, the sp2 hybridization based nanocarbon materials have excellent physical and chemical properties, as well as important applications.
So far, graphene ball, carbon nanotubes, and graphene rods that are based on sp2 hybridization have been prepared and exhibit excellent properties and widespread applications. However, further preparation of 3-D nanocarbon materials that are based on sp2 hybridization has been limited. There are references reporting that sp2 hybridization based graphene can be used to prepare porous graphene fiber. For example, Chinese Patent No. CN 102586946 discloses porous ordered high strength graphene fibers and its applications. The dispersed graphene is spun into porous graphene fibers. However, the preparation process is controlled by the dispersion and combination of graphene units, which leads to the limited integrity and continuity of the prepared porous graphene fibers. Chinese Patent No. CN 103588196 discloses hierarchical porous graphene fibers as well as its preparations and applications. Inorganic fibers are used as template, and most of graphene is grown on the surface of the inorganic fibers, which cannot form a homogeneous porous fiber structure.
Therefore, a heretofore unaddressed need exists in the art to further explore and improve 3-D nanocarbon materials so as to prepare homogeneous porous nanocarbon fibers that are based on sp2 hybridization and explore its applications.